Search Publications
Calibrating the James Webb Space Telescope Filters as Star Formation Rate Indicators
Moustakas, John; Armus, Lee; Brown, Michael J. I. +3 more
We have calibrated the 6.5 m James Webb Space Telescope (JWST) mid-infrared (MIR) filters as star formation rate (SFR) indicators, using JWST photometry synthesized from Spitzer spectra of 49 low-redshift galaxies, which cover a wider luminosity range than most previous studies. We use Balmer-decrement-corrected Hα luminosity and synthesized MIR p…
Coronal Electron Density Temperature and Solar Spectral Irradiance during Solar Cycles 23 and 24
Palacios, J.; Dal Lago, A.; Rodríguez Gómez, J. M. +1 more
Plasma parameters such as the electron density and temperature play a key role in the dynamics of the solar atmosphere. These characteristics are important in solar physics because they can help us to understand the physics of the solar corona, the ultimate goal being the reconstruction of the electron density and temperature distributions in the …
Thermal Reaction in Cometary and Pre-cometary Ices: Formation of Thiocarbamate in OCS-CH3NH2 Mixed Ices
Hodyss, Robert; Mahjoub, Ahmed
Cometary ices are rich sources of organic molecules relevant to prebiotic chemistry and may have played a key role in the delivery of the building blocks of life to Earth. Comets endure thermal processing of their surfaces during their orbits around the Sun. Furthermore, icy grain precursors of cometary materials may have experienced heating in th…
Extreme Circumgalactic H I and C III Absorption around the Most Massive, Quenched Galaxies
Ménard, Brice; Smailagić, Marijana; Prochaska, Jason Xavier +2 more
Luminous red galaxies (LRGs) are the most massive galaxies at z ∼ 0.5 and, by selection, have negligible star formation (SF). These objects have halo masses between those of L * galaxies, whose circumgalactic media (CGMs) are observed to have large masses of cold gas, and clusters of galaxies, which primarily contain hot gas. Here, we r…
An Updated Line List for NUV Spectral Synthesis in Evolved Stars: Redetermination of the Beryllium Abundance in the Solar Photosphere
Cunha, Katia; Smith, Verne V.; Carlberg, Joleen K. +1 more
Motivated by the desire to measure beryllium abundances in red giant stars, we have constructed a new line list for synthesizing spectra in the near-ultraviolet. Using the Sun, Arcturus, and Pollux as benchmark stars, we explore potential sources of missing continuous opacity and line absorption. Despite the inclusion of new sources of continuous …
Blue Straggler Stars beyond the Milky Way. II. A Binary Origin for Blue Straggler Stars in Magellanic Cloud Clusters
Deng, Licai; de Grijs, Richard; Li, Chengyuan +1 more
We have analyzed populations of blue straggler stars (BSSs) in 24 Magellanic Cloud (MC) star clusters using multi-passband Hubble Space Telescope images. We compiled a homogeneous BSS database, containing both traditional and evolved BSSs. We uncovered a sublinear correlation between the number of BSSs in the cluster cores and the clusters’ core m…
Chemical Evolution of N2H+ in Six Massive Star-forming Regions
Wang, Jun-Jie; Xu, Jin-Long; Liu, Xiao-Lan +1 more
To investigate how the abundance of N2H+ varies as massive clumps evolve, here we present a multiwavelength study toward six molecular clouds. All of these clouds contain several massive clumps in different evolutionary stages of star formation. Using archival data of the Herschel infrared Galactic Plane Survey (Hi-GAL), we m…
The Year-long Flux Variations in Boyajian's Star Are Asymmetric or Aperiodic
Hippke, Michael; Angerhausen, Daniel
We combine and calibrate publicly available data for Boyajian’s star, including photometry from ASAS (SN, V, I), Kepler, Gaia, SuperWASP, and citizen scientist observations (AAVSO, HAO, and Burke-Gaffney). Precise (mmag) photometry covers the years 2006-2017. We show that the year-long flux variations with an amplitude of ≈4% cannot be explained w…
X-Ray Study of Variable Gamma-Ray Pulsar PSR J2021+4026
Takata, J.; Zhao, J.; Lin, L. C. C. +2 more
PSR J2021+4026 showed a sudden decrease in the gamma-ray emission at the glitch that occurred around 2011 October 16, and a relaxation of the flux to the pre-glitch state at around 2014 December. We report X-ray analysis results of the data observed by XMM-Newton on 2015 December 20 in the post-relaxation state. To examine any change in the X-ray …
Cracking the Conundrum of F-supergiant Coronae
Ayres, Thomas R.
Chandra X-ray and HST far-ultraviolet (FUV) observations of three early-F supergiants have shed new light on a previous puzzle involving a prominent member of the class: α Persei (HD 20902: F5 Ib). The warm supergiant is a moderately strong, hard coronal (T∼ {10}7 K) X-ray source, but has 10 times weaker “subcoronal” Si IV 1393 Å (T∼ 8×…